Buggy code:
public final class CCombo extends Composite { Text text ; List list ; int visibleItemCount = 5 ; Shell popup ; Button arrow ; boolean hasFocus ; Listener listener ; Listener filter ; Color foreground ; Color background ; Font font ; public CCombo ( Composite parent , int style ) { } static int checkStyle ( int style ) { int mask = ( ( ( ( SWT . BORDER ) | ( SWT . READ_ONLY ) ) | ( SWT . FLAT ) ) | ( SWT . LEFT_TO_RIGHT ) ) | ( SWT . RIGHT_TO_LEFT ) ; <START_BUG> return style & mask ; <END_BUG> } public void add ( String string ) { } public void add ( String string , int index ) { } public void addModifyListener ( ModifyListener listener ) { } public void addSelectionListener ( SelectionListener listener ) { } public void addVerifyListener ( VerifyListener listener ) { } void arrowEvent ( Event event ) { } public void clearSelection ( ) { } void comboEvent ( Event event ) { } public Point computeSize ( int wHint , int hHint , boolean changed ) { } public void copy ( ) { } void createPopup ( String [ ] items , int selectionIndex ) { } public void cut ( ) { } public void deselect ( int index ) { } public void deselectAll ( ) { } void dropDown ( boolean drop ) { } char _findMnemonic ( String string ) { } Label getAssociatedLabel ( ) { } public Control [ ] getChildren ( ) { } public boolean getEditable ( ) { } public String getItem ( int index ) { } public int getItemCount ( ) { } public int getItemHeight ( ) { } public String [ ] getItems ( ) { } public boolean getListVisible ( ) { } public Menu getMenu ( ) { } public Point getSelection ( ) { } public int getSelectionIndex ( ) { } public int getStyle ( ) { } public String getText ( ) { } public int getTextHeight ( ) { } public int getTextLimit ( ) { } public int getVisibleItemCount ( ) { } void handleFocus ( int type ) { } public int indexOf ( String string ) { } public int indexOf ( String string , int start ) { } void initAccessible ( ) { } boolean isDropped ( ) { } public boolean isFocusControl ( ) { } void internalLayout ( boolean changed ) { } void listEvent ( Event event ) { } public void paste ( ) { } void popupEvent ( Event event ) { } public void redraw ( ) { } public void redraw ( int x , int y , int width , int height , boolean all ) { } public void remove ( int index ) { } public void remove ( int start , int end ) { } public void remove ( String string ) { } public void removeAll ( ) { } public void removeModifyListener ( ModifyListener listener ) { } public void removeSelectionListener ( SelectionListener listener ) { } public void removeVerifyListener ( VerifyListener listener ) { } public void select ( int index ) { } public void setBackground ( Color color ) { } public void setEditable ( boolean editable ) { } public void setEnabled ( boolean enabled ) { } public boolean setFocus ( ) { } public void setFont ( Font font ) { } public void setForeground ( Color color ) { } public void setItem ( int index , String string ) { } public void setItems ( String [ ] items ) { } public void setLayout ( Layout layout ) { } public void setListVisible ( boolean visible ) { } public void setMenu ( Menu menu ) { } public void setSelection ( Point selection ) { } public void setText ( String string ) { } public void setTextLimit ( int limit ) { } public void setToolTipText ( String string ) { } public void setVisible ( boolean visible ) { } public void setVisibleItemCount ( int count ) { } String stripMnemonic ( String string ) { } void textEvent ( Event event ) { } }

Fix:
return ( SWT . NO_FOCUS ) | ( style & mask ) ;